1. Field of the Invention
The present invention relates to a mechanism for preventing intrusion of water or the like into a boot for a universal joint that is used for a propeller shaft or the like.
2. Description of the Related Art
According to a conventional vehicle, a propeller shaft for transmitting the output of an engine to a rear wheel is divided into axle directions and back and forth parts of the divided axles are coupled by a universal joint. Then, by using a boot for preventing dust and muddy water or the like from intruding in a connecting space of an outer element and an inner element of the universal joint, one end portion of the boot is fitted in the inner element of the universal joint. The other end portion thereof is fitted in the outer element of the universal joint so that the boot is attached to the universal joint.
According to the conventional art, in order to avoid the abnormal expansion and contraction and breakage of the boot due to the change of the inner pressure of the boot based on the temperature change due to the sliding frictional heat of the universal joint and the change of the inner pressure of the boot based on the sliding of the universal joint, a groove-like communicating path for adjusting an inner pressure is provided at a fitting portion against the inner element of the boot to communicate the interior of the boot with the exterior thereof (Japanese Patent Application Laid-open (JP-A) No. 8-28704).
According to the conventional art, at the fitting portion against the inner element of the boots, its end portion to which the communicating path is opened is widely exposed to the outside world. Therefore, water or the like easily intrudes into the interior of the boot from the above-described communicating path during traveling of the vehicle and at car wash facilities with high pressure. Where a large quantity of water intrudes into the interior of the boot, it is feared that a joint function fails due to rust of the universal joint or the like.